Browsing by Subject "thermodynamic properties"

Now showing 1 - 2 of 2
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    First principles study of structural and thermodynamic properties of zirconia
    (2014) Zhang, Yi; Zhang, Jing
    Due to their high melting temperature and low thermal conductivity, zirconia (ZrO2) based ceramics have been widely used for thermal barrier coating materials. This study investigates zirconia's properties using the first principles calculations. Structural properties, including band structure, density of state, lattice parameter, as well as elastic constants for both monoclinic and tetragonal zirconia were computed. Pressure based phase transition of tetragonal zirconia (t-ZrO2) was also calculated, based on tetragonal distortion and band structure under compressive pressures. The results predicted a transition from monoclinic structure to a fluorite-type cubic structure at the pressure of 37 GPa. Moreover, monoclinic zirconia (m-ZrO2) thermodynamic property calculations were carried out. Temperature-dependent heat capacity, entropy, free energy, and the Debye temperature of monoclinic zirconia, from 0 to 1000 K, were computed and compared well with those reported in literature.
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    First principles study of thermodynamic properties of lanthanum zirconate
    (2014) Guo, Xingye; Zhang, Jing
    Lanthanum zirconia (La2Zr2O7) has become an advanced thermal barrier coating material due to its low thermal conductivity and high temperature stability. In this work, the first principles calculations were used to study the thermodynamic properties of the material. Lattice parameters, bulk and shear modulus, and specific heat of La2Zr2O7 were calculated by means of density functional theory (DFT). Hydrostatic pressure-dependent elasticity constants and bulk modulus were also studied. The thermal conductivity was calculated based on the Fourier's law. The calculated properties are in excellent agreement with the experimental and calculation results in literature.